Known in the prior art have been machine tools which make a rotary tool rotate to cut or otherwise machine a workpiece. Further, in such machine tools, there has been known a numerical control type of machine tool which designates a path of a rotary tool by coordinates of predetermined axes etc. and machines the workpiece while making the rotary tool automatically move.
In a machine tool, it is possible to perform a groove-forming operation which forms a groove part in the surface of a workpiece. In a groove-forming operation, it is possible to use an end mill or other rotary tool to cut a workpiece while changing the relative positions of the workpiece and the rotary tool so as to form a groove part which extends in a desired direction.
Japanese Patent Publication No. 11-347823A (PLT 1) discloses a cutting method which forms a deep groove by reciprocating motion of an end mill wherein the direction and magnitude of the cutting resistance are made constant in the tool feed direction. In this formation of a groove, it is possible to make the cutting resistance equal in the outbound path and the return path by setting the depths of cut different from each other. It is disclosed that by this machining method, it is possible to prevent bending or tilting of the groove or other deterioration in the shape precision.
PLT 1: Japanese Patent Publication No. 11-347823A